i think i know the answer to my question, but would like it confirming please, i have recently upgraded to a 4 foot tank because my black ghost knife fish was getting too big, i got told when i bought the knife fish it didn't interfer with any of my other fish. i have or should i say had 6 guppys (now got 3) head and tail tetra's, black widow tetra's , platy's and neons, and a small plec (new to the tank), i've just had to retrieve a body out of my tank (although they normally just disappear), do ghost knife fish munch on my other fish, i have started trying to feed the ghost knife individually, (blood worm straight into its hiding place) as i think the other fish get the food quicker, would this elevate my problem of missing fish, (trying to feed it separate) it's now about 6-7 inches, i really like this fish and have had it quite a while and would try any solutions, but if it's eating my other fish i may have to donate it back to the shop or my friend, any advice would be greatly appreciated. Also sorry for going on but the tank i bought is one of the fluval roma's that drip condensation from the lid is it ok to remove the lid top and seal it again, sorry new to tanks of this size only had smaller ones before, thanks for taking the time to read all this.